Tension key



FIG. 1 is a perspective view of a tension key;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a top view thereof;

FIG. 7 is a bottom view thereof;

FIG. 8 is a rear perspective view thereof; and,

FIG. 9 is a perspective view of the design of FIG. 1 shown in a position of use mounted on a bracket of a curtain.

The broken lines showing a headrail, bracket, and attaching screw in FIG. 9 depict environmental subject matter that forms no part of the claimed design. 

CLAIM The ornamental design for a tension key, as shown and described. 